Process for improving the storage properties of alkyl aryl sulphonates



Patented Nov. 9, 1943 UNITED STATS NATES Gilbert C. Toone, Hamburg, N. Y fassignor to Allied Chemical & Dye Corporation, a corporation of New York No Drawing. Application November 9, 1939, Serial No. 303,702

8 Claims.

This invention relates to a process for improving the storage properties of mixtures of substituted aryl sulphonates which contain as nuclear substituents radicals corresponding to the hydrocarbons present in a petroleum distillate. More particularly it relates to a process for improving the storage properties of mixed alkyl benzene sulphonates which contain as nuclear substituents radicals derivedfrom the hydrocarbons present in a kerosene fraction of petroleum.

As a comparatively recent development in the field of synthetic detergents, wetting agents. emulsifying agents, soap substitutes, and the like, there have been developed compositions consisting of mixtures of aryl sulphonates which contain as nuclear substituents radicals corresponding to the hydrocarbons present in petroleum distillates. The aryl sulphonates present in such mixtures are conveniently referred to as alkyl varyl sulphonates, the term alkyl being used in its broad sense to include cycloalkyl radicals as well as straight or branched open-chain alkyl radicals. Depending upon the purpose for which they are to be used, these mixed alkyl aryl sulphonates are derived from petroleum fractions such as fractions within the upper gasoline range, the kerosene range, and higher ranges.

For example, where compositions are desired particularly adapted foruse as wetting agents,

petroleum distillates may be employed which boil as low as 100 0., although in general petroleum distillates are not employed having a boiling point lower than the boiling point corresponding to nonane. Thus, a useful petroleum distillate for the manufacture of mixed alkyl aryl sulphonates is one boiling within the range 140 to Where it is desired to prepare a composition containing mixed alkyl aryl sulphonates in which the substituent alkyl radicals contain an average of more than carbon atoms, a petroleum usually in the presence of a condensation catalyst such as aluminum chloride or zinc chloride, sulphonating the resulting substituted aromatic compounds, neutralizing the sulphonation mass with a suitable alkaline compound, usually aqueous caustic soda, and drying the neutralized mixture. It will be understood that this process is subject to many minor variations, such as distillation of the reaction mixtures at various points. The application of L. H. Flett, Serial No. 195,414, filed March 11, 1938, now United States Patent 2,233,408 issued March 4, 1941, discloses methods for making mixed alkyl aryl sulphonates of this class.

These mixed alkyl aryl sulphonates oifer several important advantages over other available synthetic detergents. First, because of the relatively inexpensive raw materials used in their manufacture, they may be produced economically. Also, due to the fact that they consist of not one compound but of a mixture of compounds having properties varying among themselves, they are capable of a wider variety of uses than many other synthetic detergents, which are usually relatively specific in their action. In view of these facts, the mixed alkyl aryl sulphonates, particularly the alkyl benzene sulphonates, are the class of products which should be most satisfactory for general household uses. However, the mixed alkyl aryl sulphonates have the property of developing a rancid odor on being stored. While this characteristic of the mixed alkyl aryl sulphonates is not a serious handicap to their acceptance by those, engaged in using synthetic detergents in indus trial applications, this property would have an adverse eifect upon the popularization of the mixed alkyl aryl sulphonates as general household detergents.

It is an object of the present invention to provide a process for improving the storage properties of mixed alkyl aryl sulphonates of the class referred to above whereby the mixed alkyl aryl sulphonates may be stored for a relatively long period of time without developing rancid odors to an important degree. A more specific object of the invention is to provide a process for the treatment of mixed alkyl benzene sulphonates wherein the alkyl groups have been derived from a kerosene fraction of petroleum by a process including chlorination of the kerosene, condensation of resulting chlorhydrocarbons with benzene, and sulphonation of resulting alkyl benzenes, to improve. the storage properties thereof so as to Other objects of the invention in part will be obvious and in part will appear hereinafter.

It has been discovered in accordance with the present invention that a change can be effected in the properties of mixed alkyl aryl sulphonates of the above class, and particularly mixed alkyl benzene sulphonates in which the substituent alkyl groups correspond to aliphatic and alicyclic hydrocarbons of a kerosene fraction of petroleum, which have the property of developing undesirable odors upon being stored, by treating aqueous solutions of the mixed alkyl aryl sulphonates with hypochlorites so that the alkyl aryl sulphonates may be stored over a relatively long period of time without developing undesirable odors to an unpleasant degree. By this process, mixed alkyl aryl sulphonates, which in the untreated condition would be unsatisfactory for use as household detergents, are converted to a form such that they may be used satisfactorily for. this purpose.

Because of the variance between different mixed alkyl aryl sulphonates depending upon the petroleum distillates used in their preparation, the details of the process employed, the purpose for which they are to be used, and other variable factors, it is not possible to state any definite rule as to the amount of hypochlorite to be used which will be valid in all cases. In general, however, it has been found unnecessary to use an amount of hypochlorite greater than that equivalent to two and a half parts by weight of sodium mixed alkyl aryl sulphonates, and that an amount equivalent to one-quarter part of sodium hypochlorite for each 100 parts of the mixed alkyl aryl sulphonates is required even for treatment of the better samples in order to achieve noticeable improvement in the odor characteristics of the samples. In most cases an amount of hypochlorite equivalent to 0.4 to 1.6 parts by weight of sodium hypochlorite for each 100 parts by weight of th mixed alkyl aryl sulphonates is sumcient. The word equivalent is used above in its usual sense when applied to hypochlorites; i. e., an amount of one hypochlorite is equivalent to an amount of another hypochlorite when the two contain the same weight of the hypochlorite I radical.

As a result of testing numerous samples, I have devised the following test which provides a means for determining the optimum amount of hypochlorite to be used in any particular case. An aqueous solution of the mixed alkyl aryl sulphonates to be treated is prepared containing in 100 parts of solution from 8 to 12 parts of the mixed alkyl aryl sulphonates. This solution may contain in addition an inorganic salt such as sodium sulphate, with which the mixed alkyl aryl sulphonates are usually associated when made for general detergent purposes. For test purposes, to this solution, maintained at a temperature of 40 to 70 0., there are added successive small amounts of a standard 10 per cent aqueous solution of sodium hypochlorite, each addition containing about 0.0005 part by weight of sodium hypochlorite for each part of mixed alkyl aryl sulphonate in the test solution. After each addition, the solution is agitated and the period of time required for the disappearance of the hypochlorite as evidenced by the familiar potassium iodide-starch test is determined. When after an addition of hypochlorite solution the hypochlorite persists in the alkyl aryl sulphonate solution for about minutes, the optimum amount has been added.

Although in most cases it is preferred to add the optimum amount of hypochlorite, an important improvement in the storage properties of the mixed alkyl aryl sulphonates can be achieved with the use of less or more than the optimum amount. Operations in which less than the optimum amount is used may be desirable when the mixed alkyl aryl sulphonates are not to be stored for'a prolonged period and satisfactory improvement can be obtained with the use of the smaller quantity of hypochlorite. When accurate testing is not feasible because of time limitations or other factors an excess may be used. The use of two great an excess is to be avoided, however, as this results in an increase in the rate at which the mixed alkyl aryl sulphonates develop unpleasant odors, rather than the reverse. In general, the permissible excess depends upon the amount required for producing optimum results. Thus, where the optimum amount of hypochlorite is in the lower portion of the above range an excess equal to 150 per cent by weight of the optimum amount may be added and yet achieve improvement of the storage characteristics. optimum amount is in the upper portion of the range referred to above it is best not to add more than an excess equal to to per cent by weight of the optimum amount.

After treatment with the hypochlorite, the solution of mixed alkyl aryl sulphonates is dried to yield a product that may be stored over'considerably longer periods than the untreated product without developing undesirable odors to an unpleasant degree. A mixture of alkyl benzene sulphonates in which the substituent alkyl groups are derived from kerosene and which has been treated by the present process may be marketed for many purposes for which the untreated material is not suitable. Because of the state of the development of the present art it is believed to be unnecessary to enumerate all of the various types of petroleum distillates. whose derivatives may be treated in accordance with the present process to improve their odor characteristics. It is sufilcient to point out that derivatives of petroleum distillates which boil for the most part within ranges which have lower limits above 100? C., and which have the undesirable property of developing odors upon being stored, may be treated advantageously by the present process. As previously indicated,.the

Attempts made to determine the reason for v the development of unpleasant odors in the mixed alkyl. aryl sulphonates with which the present invention is concerned, and also the ex-' planation of the action of the hypochloritein the present process, have been unsuccessful;

Hence the present process is not limited to any theory of action. However, the researches leading to the development of the present invention have shown that'the process does not yield satisfactory results when applied to mixed alkl aryl sulphonates in which the aryl nucleus contains On the other hand, when the a hydroxyl group, which is capable of oxidation by a hypochlorite under the conditions of the process. For this reason, the mixed alkyl aryl sulphonates subjected to treatment by the present process are those which contain aryl nuclei free from groups oxidizable by hypochlorites under the conditions of the process. Additional examples of such groups are amino and sulphhydride groups. Examples of aromatic compounds which are free from groups oxidizable by hypochlorites under the conditions of the process are those derived;frm benzene, naphthalene, phenetole, toluene, and diphenyl.

The following examples, in which are by weight, illustrate the invention:

Example 1.-1260 parts of an aqueous solution containing 400 parts of a commercial detergent of which about 156 parts was a mixture 01! sodium alkyl benzene sulphonates (derived from a Pennsylvania or Mount Pleasant, Michigan, kerosene substantially free from olefines and aro-.

matic hydrocarbons, having a specific gravity between 0.785 and 0.795 at 24 C., 95 per cent of which boils between 180 and 300 C., and 80 per cent between 200 and 280 C. at atmospheric pressures, by a process involving chlorinating the kerosene, condensing resulting chlorhydrocare bons with benzene, sulphonating resulting condensation products, and neutralizing the sulphonated condensation products with caustic soda) and about 244 parts was anhydrous sodium sulphate, were warmed to a temperature between about 50 and about 60 C., and in glass apparatus treated with a series of small additions, for example, about 1 part per addition, of a the parts i per cent by weight solution of sodium hypochlorite (caustic soda alkaline), until the hypochlorite persisted in the solution, as detected by av KI-starch test, for 5 minutes after the last addition of hypochlorite was made.

The addition was found sufiicient when this.

slow rate of decomposition of the hypochlorite,

i. e., its perisistence in the solution for about 5 minutes, was reachedl The amount of hypochlorite was equal to 0.62 part NaOCl per 100 parts of sodium alkyl benzene sulphonates in the solution. After the final addition of hypochlorite, the treated solution was allowed to stand at to C. until the hypochlorite had disappeared; the solution was adjusted to a neutral reaction (i. e., to a pH between 6.6 and 7.6) and evaporated and dried in the usual way. The dry product, after being stored for 10 months, had developed some objectionable rancid odor, but far less so than sodium alkyl benzene sulphonates which had been stored for the same period and had been made from a portion of the same but untreated commercial detergent solution.

Example 2.In this example a mixture of sodium alkyl benzene sulphonates which was derived from a Pennsylvania kerosene having a specific gravity of 0.788 at 24 C. and a boiling range of 185 to 275 C. was used. The mixture was-prepared by chlorinating the kerosene in the presence of a small amount of iodine until the amount of chlorine taken up corresponded to 115 per cent of monochlorination, based on the average molecular weight of the hydrocarbons in the kerosene. The chlorinated kerosene was then condensed with benzene in the presence of anhydrous aluminum chloride, after which a tarry layer that formed was separated I from theremainder of the mixture consisting of alkylated benzenes and unreacted materials/ After removing low-boiling hydrocarbons, chiefly riod of 16 hours.

benzene, by distillation, a fraction of the mixture consisting chiefly of alkylated benzenes was collected. This fraction was then sulphonated with 100 per cent sulphuric acid, and a mixture of sulphonic acids of the alkylated benzenes was recovered. This mixture was drowned in ice Portion A-Was dried without treatment with sodium hypochlorite solution.

Portion B-Was treated with an amount of aqueous sodium hypochlorite corresponding to 0.92 part sodium hypochlorite for each 100 parts of the mixture of sodium alkyl benzene sulphonates in the solution and dried.

Portion C--Was treated with 1.58 parts of sodium hypochlorite per 100 parts of the mixture of sodium alkyl benzene sulphonates in the solution, and dried.

The portions were compared after the dry products from them were subjected to an accelerated aging test in which the said products were maintained at a temperature of about C. for a pe- It was found that the dry product from treated portion B had developed slightly less rancid odor than had the dry product from treated portion C, and that both of these products had developed considerably less odor than the dry product of portion A.

The dry products were 'stored for about one year, and again compared. The same order of superiority was found; but rancidity in the sample representing the dried product of portion C had developed so much more than in] the sample representing portion B that the difleren'ce in rancidity was much more distinct than that found in the foregoing accelerated aging test.

From these tests it will be seen that the use of even a. relatively large excess of hypochlorite (portion C) produces marked improvement in the products but that where the products are to be stored for a long period of time such as a year or more it is desirable to use an amount oi hypochl'orite more closely approaching the optimum.

In regard to the hypochlorite treatment described in the examples, it'is pointed out that hypochlorites have frequently been employed for the purpose of improving the color of chemical compounds. The amount of hypochlorite that would be required merely to decolorize the mixed alkyl aryl suphonates of the examples is much less than that required for the purposes of the present process.

It will be understood that the above examples are merely illustrative of the manner in which the present process may be practiced. For example, it is not necessary that the hypochlorite be added in small portions since a preliminary test of a portion of the solution of the mixed alkyl aryl sulphonates can be made and then the proper amount of hypochlorite as determined by this test can be added in one batch to the solution of mixed alkyl aryl sulphonates.

The effect of the hypochlorite in the present process does not vary with the concentration of the mixed alkyl aryl sulphonates present in the solution undergoing treatment; that is'the solution subjected to treatment maybe a dilute solution or a concentrated solution and in either case the eilfect of a given amount of hypochlorite is substantially the same. The mixed alkyl aryl sulphonates are generally employed in the form of their sodium salts. Since it is usually desirable to have all the salts present in the mixed alkyl aryl sulphonates as sodium salts, and also because of economic and technical advantages, it is generally preferable to use sodium hypochlorite in the process. If desired, however, other hypochlorites may be used such as, for example, potassium hypochlorite and magnesium hypochlori Further, it will be understood by those skilled in the art that other methods of introducing the hypochlorite into the solution than those described in the examples come in for consideration. For example, it is well known that a hypochlorite can be formed in situ by introducing chlorine into an alkaline solution of the material to be treated.

The treatment with the hypochlorite is carried out on alkyl aryl sulphonate solutions which are slightly alkaline or neutral. The average type of hypochlorite solution can be used; for example, one which contains from 5 to about parts by weight of sodium hypochlorite per 100 parts by weight of its solution is satisfactory. Such a solution is usually alkaline and the alkalinity introduced into the alkyl aryl sulphonate solution is not undesirable during the treatment. At the end of the treatment the alkalinity thus introduced may be reduced if desired by the addition of small amounts of sulphuric or hydrochloric acid before the solution is dried.

The process preferably is carried out while the alkyl aryl sulphonate solution is maintained at a temperature between about and 70 C., because within this temperature range the reaction with the hypochlorite takes place at an easily recognized and controllable rate. However, the treatment may be carried out at temperatures outside of this range although it will be understood that the rate of reaction is affected by the temperature maintained. A It will thus be seen that the present invention provides a simple and economical process whereby the storage properties of mixed alkyl aryl sulphonates derived from petroleum distillates may be improved so that the mixed alkyl aryl sulphonates may be kept for a considerable period of time without developing rancid odors to an undesirable degree.

Since certain changes may be made in the process described above without departing from the scope of the invention it will be understood that the above description should be taken as illustrative and not in a limiting sense.

I claim:

1. The process for improving the storage properties of a mixture of alkyl aryl sulphonates in which the aryl nucleus is free from groups oxidizable by hypochlorites and the alkyl groups are derived from a petroleum distillate which boils for the most part above 100 C., which comprises treating an aqueous solution of said mixture of alkyl aryl sulphonates with an amount of a hypochlorite equivalent to an amount of'sodium hypochlorite lying within a range of which the minimum is determined by the following procedure: introducing a 10 per cent by weight solution of sodium hypochlorite into 100 parts by weight of an aqueous solution of said mixture'of alkyl aryl sulphonates containing 8 to 12 .parts by weight of said mixture, while maintaining the temperature at from 40 to 70 C.,.in a series of additions each containing about 0.0005 part by weight of sodium hypochlorite for each part of mixture of. alkyl aryl sulphonates in said 100 parts of aqueous solution, until, after the last addition of sodium hypochlorite, hypochlorite persists in the alkyl aryl sulphonate solution for a period of about 5 minutes as determined by a, potassium iodide-starch test-and of which range the maximum amount oi sodium hypochlorite is 250 per cent or said minimum amount when said minimum amount is in the neighborhood of one quarter part by weight for each 100 parts by weight of said mixture of alkyl aryl sulphonates, and 120 per cent or said minimum amount when said minimum amount is in the neighborhood of two and one-half parts by weight for each 100 parts by weight of said mixture of alkyl aryl sulphonates, whereby said mixture of alkyl aryl sulphonates in dry form is capable of being stored for a longer period of time, without developing unpleasant odors to an undesirable degree, than an identical mixture of alkyl aryl sulphonates which has not been subjected to said treatment.

2. The process for improving the storage properties of a mixture of alkyl aryl sulphonates in which the aryl nucleus is free from groups oxidizable by hypochlorite's, which mixture has been prepared by a process involving chlorinating a kerosene fraction of petroleum which boils for the most part within the range of 180 to 300 C., condensing resulting chlorhydrocarbons with an aromatic compound free from groups oxidizable by hypochlorites, and sulphonating resulting condensation products, which comprises treating an aqueous solution of said mixture of alkyl aryl sulphonates with an amount of a hypochlorite equivalent to an amount of sodium hypochlorite lying within a range of which the minimum is determined by the following procedure: introducing a 10 per cent by weight solution of sodium hypochlorite into parts by weight of an aqueous solution of said mixture of alkyl aryl sulphonates containing 8 to 12 parts by weight of said mixture, while maintaining the temperature at from 40 to 70 C., in a series of additions each containing about 0.0005 part by weight of sodium hypochlorite for each part of mixture of alkyl aryl sulphonates in said 100 parts of aqueous solution, until, after the last addition of sodium hypochlorite, hypochlorite persists in the alkyl aryl sulphonate solution for a period of about 5 minutes as determined by a potassium iodide-starch test--and of which range the'maximum amount of sodium hypochlorite is 250 per cent of said minimum amount when said minimum amount is in the neighborhood of one-quarter part by weight for each 100 parts by weight of said mixture of alkyl aryl sulphonates, and per cent of said minimum amount when said minimum amount is in the neighborhood of two and one-half parts by weight for each 100 parts by weight of said mixture of alkyl aryl sulphonates, whereby said mixture of alkyl aryl sulphonates in dry form is capable of being stored for a longer period of time without developing unpleasant odors to an undesirable degree than an identical mixture of alkyl aryl sulphonates which has not been subjected to said treatment.-

3. The process for improving the storage properties of a mixture of sodium alkyl benzene sulphonates which has been prepared by a process involving chlorinating a kerosene fraction of petroleum which boils for the most part within the range of 180 to 300 C. condensing resulting chlorhydrocarbons with benzene, and sulphonating resulting condensation products, which comprises treating an aqueous solution of said mixture of sodium alkyl benzene sulphonates with an amount of a hypochlorite equivalent to an amount of sodium hypochlorite lying within a range of which the is determined by the following procedure: introducing a per cent by weight solution of sodium hypochlorite into 100 parts by weight of an aqueous solution of said mixture of sodium alkyl benzene sulphonates containing 8 to 12 parts by weight of said mixture, while maintaining the temperature at from 40 to 70 C., in a series of additions each containing about 0.0005 part by weight of sodium hypochlorite for each part of mixture of sodium alkyl benzene sulphonates in said 100 parts of aqueous solution, until, after the last addition of sodium hypochlorite, hypochlorite persists in the sodium alkyl benzene sulphonate solution for a period of about 5 minutes as determined by a potassium iodide-starch testand of which range the maximum amount of sodium hypochlorite is 250 per cent of said minimum amount when said minimum amount is in the neighborhood oi one-quarter part by weight for each 100 parts by weight of said mixture of sodium alkyl benzene sulphonates, and 120 per cent of said minimum amount when said minimum amount is in the neighborhood of two and one-half parts by weight for each 100 parts by weight of said mixture of sodium alkyl benzene sulphonates, whereby said mixture of sodium alkyl benzene sulphonates in dry form is capable of being stored for a longer period of time without developing unpleasant odors to an undesirable degree than an identical mixture of alkyl aryl sulphonates which has not been subjected to said treatment.

4. The process for improving the storage properties of a mixture of alkyl aryl sulphonates in which the aryl nucleus is free from groups oxidizable by hypochlorites and the alkyl groups are derived from a petroleum distillate which boils for the most part above 100 C., which comprises treating an aqueous solution of said mixture of alkyl aryl sulphonates with an amount of a hypochlorite which is equivalent to an amount of which the aryl nucleus is free from groups oxisodium hypochlorite suflicient to inhibit odor development but not exceeding two and a half parts by weight of sodium hypochlorite for each 100 parts by weight of said mixture of alkyl aryl sulphonates, whereby said mixture of alkyl aryl sulphonates in dry form is capable of being stored for a longer period of time without developing unpleasant odors to an undesirable degree than an identical mixture of alkyl aryl sulphonates which has not been subjected to said treatment.

5. The process for improving the storage properties of a mixture of alkyl aryl sulphonates in which the aryl nucleus is free from groups oxidizable by hypochlorites and the alkyl groups are derived from a kerosene fraction of petroleum which boils for the most part within the range of 180 to 300 C., which comprises treating an aqueous solution of said mixture of alkyl aryl sulphonates with an amount of a hypochlorite which is equivalent to an amount or sodium hypochlorite within the range or one-quarter to dizable by hypochlorites and the alkyl groups are derived from a kerosene fraction of petroleum which boils for the most part within the range of 180 to 300 C., which comprises treating an aqueous solution of said mixture of alkyl aryl sulphonates with an amount of sodium hypochlorite within the range of one-quarter to two and a half parts by weight of sodium hypochlorite for each parts by weight of said mixture of alkyl aryl sulphonates, whereby said mixture of alkyl aryl sulphonates in dry form is capable oi being stored for a longer period of time without developing unpleasant odors to an undesirable degree than anidenticaLmixture of alkyl aryl sulphonates which has not been subjected to said treatment.

7. The process for improving the storage properties of a mixture of sodium alkyl benzene sulphonates in which, the alkyl groups are derived from a kerosene fraction of petroleum which boils for the most part within the range of to 300 C., which comprises treating an aqueous solution of said mixture of sodium alkyl benzene sulphonates with an amount of sodium hypochlorite suflicient to inhibit odor development but not exceeding two and a half parts by weight of sodium hypochlorite for each 100 parts by weight of said mixture of sodium alkyl benzene sulphonates, whereby said mixture of sodium alkyl benzene sulphonates in dry form is capable of being stored for a longer period of time without developing unpleasant odors to an undesirable degree than an identical mixture of sodium alkyl henzene sulphonates which has not been subjected to said treatment.

8. The process for improving the storage prop erties of a mixture of sodium alkyl benzene sulphonates prepared by a process involving chlorinating a kerosene fraction of petroleum composed predominantly of hydrocarbons selected fro the group consisting of aliphatic and alicyclic hydrocarbons and which boils for the most part within the range of 180 to 300 C., condensing resulting chlorhydrocarbons with benzene in the presence of aluminum chloride, and sulphonating resulting condensation products, which comprises treating an aqueous solution of said mixture of sodium alkyl benzene sulphonates with an amount of sodium hypochlorite within the' range of one-quarter to two and a half parts by weight of sodium hypochlorite for each 100 parts by weight of said mixture of sodium alkyl benzene sulphonates, whereby said mixture of sodium alkyl benzene sulphonates in dry form is capable of being stored for a longer period or time without developing unpleasant odors to an undesirable degree than an identical mixture of sodium alkyl benzene.sulphonates which has not been subjected to said treatment.

GILBERT C. 'I'OONE. 

